Riley O'Brien has firmly established himself as the man closing games for the St. Louis Cardinals, building on a strong 2025 second half where he posted a 2.10 ERA. His current run is impressive; entering Tuesday, O'Brien saved four of his last six outings while facing only 20 batters and allowing just one hit. This emergence makes him a must-add for fantasy players who overlooked the 31-year-old journeyman during preseason drafts.

O'Brien’s success stems from heavy reliance on his 97.5 mph sinker, thrown 61% of the time, coupled with a high 75% ground ball rate among right-handed relievers. He joins Mason Miller as the only pitchers with four-plus saves and zero earned runs allowed so far this season. Meanwhile, other established arms face scrutiny; Edwin Diaz saw his fastball velocity drop to 95.9 mph this season, prompting concern after a blown save opportunity.

Elsewhere in the league, Jakob Junis shockingly leads the Rangers with three saves, surpassing his total from the prior nine seasons combined following a $4 million deal. Conversely, David Bednar’s early numbers with the Yankees are concerning, boasting an alarming 2.25 WHIP despite high expectations. Fantasy managers must navigate this volatility, as even trusted closers like Diaz and Bednar show early cracks that open doors for others.